Spring3 MVC的最佳实践和理解（7）

 

个人学习参考所用，勿喷！ 

 

7.表单处理和多页表单向导

7.1）表单处理。

表单处理很常见。比如我们有下面的表单：

<form:form method="post" modelAttribute="reservation">
<form:errors path="*" cssClass="error" />
<table>
  <tr>
    <td>Court Name</td>
    <td><form:input path="courtName" /></td>
    <td><form:errors path="courtName" cssClass="error" /></td>
  </tr>
  <tr>
    <td>Date</td>
    <td><form:input path="date" /></td>
    <td><form:errors path="date" cssClass="error" /></td>
  </tr>
  <tr>
    <td>Hour</td>
    <td><form:input path="hour" /></td>
    <td><form:errors path="hour" cssClass="error" /></td>
  </tr>
  <tr>
    <td>Player Name</td>
    <td><form:input path="player.name" /></td>
    <td><form:errors path="player.name" cssClass="error" /></td>
  </tr>
  <tr>
    <td>Player Phone</td>
    <td><form:input path="player.phone" /></td>
    <td><form:errors path="player.phone" cssClass="error" /></td>
  </tr>
  <tr>
    <td colspan="3"><input type="submit" /></td>
  </tr>
</table>
</form:form>

 

这里使用的是spring的标签,HTML中需要<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>。 很多属性一看就知道含义。需要注意的是，modelAttribute属，这里联想下Struts2中的值栈就能够明白这里代表的是处理的返回结果。

编写后台的控制器类：

@Controller
// Bind controller to URL /reservationForm
// initial view will be resolved to the name returned in the default GET method
@RequestMapping("/reservationForm")
// Add Reservation object to session, since its created on setup and used after submission
@SessionAttributes("reservation") // Command name class was used in earlier Spring versions
public class ReservationFormController {
    private ReservationService reservationService;

    // Wire service in constructor, available in application context 
    @Autowired
    public ReservationFormController(ReservationService reservationService) {
        this.reservationService = reservationService;
    }

    // Create attribute for model 
    // Will be represented as drop box Sport Types in reservationForm
    @ModelAttribute("sportTypes")
    public List<SportType> populateSportTypes() {
        return reservationService.getAllSportTypes();
    }

    // Controller will always look for a default GET method to call first, irrespective of name
    // In this case, named setupForm to ease identification
    @RequestMapping(method = RequestMethod.GET)
    public String setupForm( @RequestParam(required = false, value = "username") String username,
						Model model) {
        Reservation reservation = new Reservation();
        reservation.setPlayer(new Player(username, null));
        model.addAttribute("reservation", reservation);
        return "reservationForm";
    }

    // Controller will always look for a default POST method irrespective of name
    // when a submission ocurrs on the URL (i.e.@RequestMapping(/reservationForm)) 
    // In this case, named submitForm to ease identification
    @RequestMapping(method = RequestMethod.POST)
    // Model reservation object, BindingResult and SessionStatus as parameters 
    public String submitForm(@ModelAttribute("reservation") Reservation reservation,
            BindingResult result, SessionStatus status) { 
        reservationService.make(reservation);
		return "redirect:reservationSuccess";
    }
}

 需要注意的是@SessionAttributes("reservation")注解和submitForm(...)方法的返回值方式return "redirect:reservationSuccess"。

@SessionAttributes是的reservation对象唯一的存在于用户会话中，目的是为了保持用户每次提交的数据（用户提交可能会出错，所以不是一次提交就一定能够成功）。

"redirect:reservationSuccess"逻辑视图表明重定向到reservationSuccess逻辑视图，应用中设定是返回reservationSuccess.jsp，这样做的目的是为了防止提交成功后的刷新造成再次提交。这里应用了post/redirect/get设计模式来处理这个问题。

 

提供表单参考数据。例如这里的体育类型查考选择框：

<tr>
<td>Sport Type</td>
<td>
  <form:select path="sportType" items="${sportTypes}"
	itemValue="id" itemLabel="name" />
</td>
<td><form:errors path="sportType" cssClass="error" /></td>
</tr>

 

这里需要在控制器中添加一个@ModelAttribute("sportTypes") 标识的模式属性sportTypes（@ModelAttribute用于定义全局模式属性），在前面的submitForm(...)中也有@ModelAttribute("reservation") 用于应用session中的reservation对象。

@ModelAttribute("sportTypes")
public List<SportType> populateSportTypes() {
	return reservationService.getAllSportTypes();
}

 

绑定自定义类型的属性。上述的SportType属性提交到处理程序是一个String id = "1" 的字符串类型，我们需要的是String  sportType= "棒球" 这样字段。那么这里需要如同Struts2中的转换器相同功能的实现方式：

public class SportTypeEditor extends PropertyEditorSupport {

    private ReservationService reservationService;

    public SportTypeEditor(ReservationService reservationService) {
        this.reservationService = reservationService;
    }

    public void setAsText(String text) throws IllegalArgumentException {
        int sportTypeId = Integer.parseInt(text);
        SportType sportType = reservationService.getSportType(sportTypeId);
        setValue(sportType);
    }
}

 

有了这个转换实现类，我们现在需要将其对应的控制器类联系起来，这里需要编写自己的WebBindingInitializer实现：

public class ReservationBindingInitializer implements WebBindingInitializer {

    private ReservationService reservationService;

    @Autowired
    public ReservationBindingInitializer(ReservationService reservationService) {
        this.reservationService = reservationService;
    }

    public void initBinder(WebDataBinder binder, WebRequest request) {
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        dateFormat.setLenient(false);
        binder.registerCustomEditor(Date.class, new CustomDateEditor(
                dateFormat, true));
        binder.registerCustomEditor(SportType.class, new SportTypeEditor(
                reservationService));
    }
}

 

还需要在应用上下文中进行配置注册：

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
	<property name="webBindingInitializer">
		<bean class="com.apress.springrecipes.court.web.ReservationBindingInitializer" />
	</property>
</bean>

 

 

表单的校验。表单成功提交前的校验在服务器端也需要做不仅是标准的做法，尤其在请求来自不支持JavaScript的wap终端时。这里可以编写如下的检验类：

@Component
public class ReservationValidator implements Validator {

    public boolean supports(Class<?> clazz) {
        return Reservation.class.isAssignableFrom(clazz);
    }

    public void validate(Object target, Errors errors) {
        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "courtName",
                "required.courtName", "Court name is required.");
        ValidationUtils.rejectIfEmpty(errors, "date",
                "required.date", "Date is required.");
        ValidationUtils.rejectIfEmpty(errors, "hour",
                "required.hour", "Hour is required.");
        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "player.name",
                "required.playerName", "Player name is required.");
        ValidationUtils.rejectIfEmpty(errors, "sportType",
                "required.sportType", "Sport type is required.");

        Reservation reservation = (Reservation) target;
        Date date = reservation.getDate();
        int hour = reservation.getHour();
        if (date != null) {
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(date);
            if (calendar.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) {
                if (hour < 8 || hour > 22) {
                    errors.reject("invalid.holidayHour", "Invalid holiday hour.");
                }
            } else {
                if (hour < 9 || hour > 21) {
                    errors.reject("invalid.weekdayHour", "Invalid weekday hour.");
                }
            }
        }
    }
}

 @Component注解告诉Spring实例化该类为与类名一样的Bean，这里为reservationValidator。这里需要像激活@Controller一样的激活改类所在的包。

然后在ReservationFormController控制器中添加添加使用刚刚定义的校验器：

@Controller
@RequestMapping("/reservationForm")
@SessionAttributes("reservation")
public class ReservationFormController {
    private ReservationService reservationService;
    private ReservationValidator validator;

    @Autowired
    public ReservationFormController(ReservationService reservationService, 
	    ReservationValidator validator) {
        this.reservationService = reservationService;
        this.validator = validator;
    }

    @ModelAttribute("sportTypes")
    public List<SportType> populateSportTypes() {
        return reservationService.getAllSportTypes();
    }

    @RequestMapping(method = RequestMethod.GET)
    public String setupForm(Model model) {
        Reservation reservation = new Reservation();
        reservation.setPlayer(new Player(username, null));
        model.addAttribute("reservation", reservation);
        return "reservationForm";
    }

    @RequestMapping(method = RequestMethod.POST)
    public String submitForm(@ModelAttribute("reservation") Reservation reservation,
            BindingResult result, SessionStatus status) { 
        validator.validate(reservation, result);	
        if (result.hasErrors()) {
            return "reservationForm";
        } else {
            reservationService.make(reservation);
			status.setComplete();
            return "redirect:/reservationSuccess";
        }
    }
}

 

 这里通过ReservationValidator的校验，如果有错误则返回错提示。一旦校验成功，完成提交后，需要通过status.setComplete()来释放@SessionAttributes("reservation")中的reservation对象，以此来处理到期的控制器的回话数据。

 

7.2）向导表单。

处理跨越多页的向导表单（Wizard forms），需要为向导控制器定义多个视图，一个控制器管理所有这些表单数据的状态。现在需要使用向导表单来完成预订球场功能，请求domain代码如下：

public class PeriodicReservation {
    private String courtName;
    private Date fromDate;
    private Date toDate;
    private int period;
    private int hour;
    private Player player;
    //getter an setter
	...
}

 

 表单向导页依次分为如下三页：

reservationPlayerForm.jsp

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!-- 添加页面编码设置来解决编码问题 -->
<%@page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>  
<html>
<head>
<title>Reservation Court Form</title>
<style>
.error {
  color: #ff0000;
  font-weight: bold;
}
</style>
</head>

<body>
<form:form method="post" modelAttribute="reservation">
<table>
  <tr>
    <td>Court Name</td>
    <td><form:input path="courtName" /></td>
    <td><form:errors path="courtName" cssClass="error" /></td>
  </tr>
  <tr>
    <td colspan="3">
      <input type="hidden" value="0" name="_page"/>
      <input type="submit" value="Next" name="_target1" />
      <input type="submit" value="Cancel" name="_cancel" />
    </td>
  </tr>
</table>
</form:form>
</body>
</html>

reservationTimeForm.jsp

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!-- 添加页面编码设置来解决编码问题 -->
<%@page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>  
<html>
<head>
<title>Reservation Time Form</title>
<style>
.error {
  color: #ff0000;
  font-weight: bold;
}
</style>
</head>

<body>
<form:form method="post" modelAttribute="reservation">
<table>
  <tr>
    <td>From Date</td>
    <td><form:input path="fromDate" /></td>
    <td><form:errors path="fromDate" cssClass="error" /></td>
  </tr>
  <tr>
    <td>To Date</td>
    <td><form:input path="toDate" /></td>
    <td><form:errors path="toDate" cssClass="error" /></td>
  </tr>
  <tr>
    <td>Period</td>
    <td><form:select path="period" items="${periods}" /></td>
    <td><form:errors path="period" cssClass="error" /></td>
  </tr>
  <tr>
    <td>Hour</td>
    <td><form:input path="hour" /></td>
    <td><form:errors path="hour" cssClass="error" /></td>
  </tr>
  <tr>
    <td colspan="3">
      <input type="hidden" value="1" name="_page"/>
      <input type="submit" value="Previous" name="_target0" />
      <input type="submit" value="Next" name="_target2" />
      <input type="submit" value="Cancel" name="_cancel" />
    </td>
  </tr>
</table>
</form:form>
</body>
</html>

 

reservationPlayerForm.jsp

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!-- 添加页面编码设置来解决编码问题 -->
<%@page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>  
<html>
<head>
<title>Reservation Player Form</title>
<style>
.error {
  color: #ff0000;
  font-weight: bold;
}
</style>
</head>

<body>
<form:form method="post" modelAttribute="reservation">
<table>
  <tr>
    <td>Player Name</td>
    <td><form:input path="player.name" /></td>
    <td><form:errors path="player.name" cssClass="error" /></td>
  </tr>
  <tr>
    <td>Player Phone</td>
    <td><form:input path="player.phone" /></td>
    <td><form:errors path="player.phone" cssClass="error" /></td>
  </tr>
  <tr>
    <td colspan="3">
      <input type="hidden" value="2" name="_page"/>
      <input type="submit" value="Previous" name="_target1" />
      <input type="submit" value="Finish" name="_finish" />
      <input type="submit" value="Cancel" name="_cancel" />
    </td>
  </tr>
</table>
</form:form>
</body>
</html>

上面三个视图中包含了pre、next、submit和cancel按钮。控制器代码如下： 

@Controller
@RequestMapping("/periodicReservationForm")
@SessionAttributes("reservation")
public class PeriodicReservationController {

    private ReservationService reservationService;
    @SuppressWarnings("unused")
	private PeriodicReservationValidator validator;

    @Autowired
    public PeriodicReservationController(ReservationService reservationService,
             PeriodicReservationValidator periodicReservationValidator) {
        this.reservationService = reservationService;
	this.validator = periodicReservationValidator;
    }

 
    @RequestMapping(method = RequestMethod.GET)
    public String setupForm(Model model) {	
        PeriodicReservation reservation = new PeriodicReservation();
        reservation.setPlayer(new Player());
        model.addAttribute("reservation", reservation);
        return "reservationCourtForm";
    }

    @SuppressWarnings({ "rawtypes", "unchecked" })
    @RequestMapping(method = RequestMethod.POST)
    public String submitForm(
	    HttpServletRequest request, HttpServletResponse response,
            @ModelAttribute("reservation") PeriodicReservation reservation,
            BindingResult result, SessionStatus status,
	    @RequestParam("_page") int currentPage, Model model) {	
	Map pageForms = new HashMap();
	pageForms.put(0,"reservationCourtForm");// Mapped to /WEB-INF/jsp/reservationCourtForm.jsp
	pageForms.put(1,"reservationTimeForm");// Mapped to /WEB-INF/jsp/reservationTimeForm.jsp
	pageForms.put(2,"reservationPlayerForm");// Mapped to /WEB-INF/jsp/reservationPlayerForm.jsp
	if (request.getParameter("_cancel") != null) {
	    return (String)pageForms.get(currentPage);	    
	} else if (request.getParameter("_finish") != null) {
	    new PeriodicReservationValidator().validate(reservation, result);
	    if (!result.hasErrors()) { 
		reservationService.makePeriodic(reservation);
		status.setComplete();
		return "redirect:reservationSuccess";
	    } else {
		return (String)pageForms.get(currentPage);	    
	    }
	} else {
	    int targetPage = WebUtils.getTargetPage(request, "_target", currentPage);
	    if (targetPage < currentPage) {
		return (String)pageForms.get(targetPage);
	    } 
	    switch (currentPage) {
   	        case 0: 
		    new PeriodicReservationValidator().validateCourt(reservation, result); break;
	        case 1: 
		    new PeriodicReservationValidator().validateTime(reservation, result); break;
    	        case 2: 
		    new PeriodicReservationValidator().validatePlayer(reservation, result); break;
	    }
	    if (!result.hasErrors()) {
		return (String)pageForms.get(targetPage);
	    } else { 
		return (String)pageForms.get(currentPage);
	    }
	}
    }
    
    @ModelAttribute("periods")
    public Map<Integer, String> periods() {	
	Map<Integer, String> periods = new HashMap<Integer, String>();
	periods.put(1, "Daily");
	periods.put(7, "Weekly");
        return periods;
    }
}

 

 这里还是用HTTP GET方法来初始化空表单，用一个HTTP POST处理方法来处理前进、后退、提交和退出等事件。不同页面中的数据都用@SessionAttributes("reservation")的唯一的会话对象中。在这里还添加对数据的校验功能，而且需要特别注意上面对每次next步骤中的数据校验，可以看到校验器代码如下：

@Component
public class PeriodicReservationValidator implements Validator {

    public boolean supports(Class<?> clazz) {
        return PeriodicReservation.class.isAssignableFrom(clazz);
    }

    public void validate(Object target, Errors errors) {
        validateCourt(target, errors);
        validateTime(target, errors);
        validatePlayer(target, errors);
    }

    public void validateCourt(Object target, Errors errors) {
        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "courtName",
                "required.courtName", "Court name is required.");
    }

    public void validateTime(Object target, Errors errors) {
        ValidationUtils.rejectIfEmpty(errors, "fromDate",
                "required.fromDate", "From date is required.");
        ValidationUtils.rejectIfEmpty(errors, "toDate", "required.toDate",
                "To date is required.");
        ValidationUtils.rejectIfEmpty(errors, "period",
                "required.period", "Period is required.");
        ValidationUtils.rejectIfEmpty(errors, "hour", "required.hour",
                "Hour is required.");
    }

    public void validatePlayer(Object target, Errors errors) {
        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "player.name",
                "required.playerName", "Player name is required.");
    }
}

 

 这种更加细粒度的校验实现对分页表单相当来说是最好的检验方式。

 

 

参考：

juyon的blog:《spring3 MVC国际化支持之中文乱码》

Gary Mark等的书籍：《Spring Recipes》2ed